The sum of the digits of a two-digit number is 9. Also, nine times this number is twice the number obtained by reversing the order of the digits. Find the number.
Let the number be “ab”
Its value is 10a + b
a + b = 9 ---------- (1)
Also
9(10a + b) = 2(10b+a)
8a –b = 0 ---------- (2)
Solving, we get a= 1, b= 8
Hence our number is 18